3D Printing Magnetic Actuators for Biomimetic Applications

Abstract

Biomimetic actuators with stimuli-responsiveness, adaptivity, and designability have attracted extensive attention. Recently, soft intelligent actuators based on stimuli-responsive materials have been gradually developed, but it is still challenging to achieve various shape manipulations of actuators through a simple 3D printing technology. In this paper, a 3D printing strategy based on magneto-active materials is developed to manufacture various biomimetic magnetic actuators, in which the new printable magnetic filament is composed of a thermoplastic rubber material and magnetic particles. The continuous shape transformation of magnetic actuators is further demonstrated to imitate the motion characteristic of creatures, including the predation behavior of octopus tentacles, the flying behavior of the butterfly, and the flower blooming behavior of the plant. Furthermore, the magnetic field-induced deformation of the biomimetic structure can be simulated by the finite element method, which can further guide the structural design of the actuators. This work proves that the biomimetic actuator based on soft magneto-active materials has the advantages of programmable integrated structure, rapid prototyping, remote noncontact actuation, and rapid magnetic response. As a result, this 3D printing method possesses broad application prospects in soft robotics and other fields.

3D/4D Printing of Polymers: Fused Deposition Modelling (FDM), Selective Laser Sintering (SLS), and Stereolithography (SLA)

“…AM is transforming the manufacturing industry with the ability to produce geometrically simple to highly complex and delicate structures. With a variety of 3D printing processes available for a wide range of materials, 3D printing has been extensively adopted in a number of different fields including but are not limited to mechanical engineering, civil [253], (b) 4D effect of a gripper under an external magnetic field, produced via SLS printing [266], and (c) 4D effect of flower-like structure and folding of 2D to the 3D structure under an external magnetic field, produced via DLP printing [255].…”

“…There are, however, other printing methods such as direct ink write (DIW) where nano to micron-sized fillers have been used successfully to a greater extent [236,[249][250][251]. The filler materials should facilitate the re-extrudability of composite filaments for FDM [252,253], production of composite or surface decorated (with nanofillers) micro powders for SLS [254], and high stability in the liquid resin for SLA/DLP [255][256][257]. Please note that the pure SLA here is modified to its variants, to direct laser processing (DLP) or micro-continuous liquid interface production (μCLIP) or two-photon polymerization (2PP).…”

“…For instance, the original filament material (i.e., thermoplastic rubber) was heated to 70 • C to soften the surface then the magnetic fillers (i.e., CIPs) were added and mixed thoroughly. After that, a twin extruder was used to produce a composite filament [253]. In another study, PCL or TPU were mechanically mixed with CIPs first and then hot melted (at 200 • C) within the extruder and the composite filament was extruded [252].…”

“…There are a number of different studies where both materials and processes for vat-based printing of composite inks are studied in detail, refer to [255,256,[269][270][271]. (a) Composite filament formation method (adapted from [253]), (b) composite powder formation method (adapted from [254]), (c) composite ink formation method (adapted from [256]), (d) examples of thermal and chemical properties of modified PLA-iron oxide composite filaments for FDM (adapted from [265]), (e) examples of thermal properties of modified PA12-iron oxide composite powder for SLS (adapted from [254]), and (f) rheological properties of acrylate iron oxide composite ink for DLP (adapted from [255]).…”

“…Examples of shape-morphing phenomenon demonstrated by 4D printed magnetic structures. (a) 4D effect of the flower-like biomimetic magnetic actuator under an external magnetic field, produced via FDM printing[253], (b) 4D effect of a gripper under an external magnetic field, produced via SLS printing[266], and (c) 4D effect of flower-like structure and folding of 2D to the 3D structure under an external magnetic field, produced via DLP printing[255].…”